FIELD OF THE INVENTION
The present invention relates to a magnetic recording and reproducing apparatus and a magnetic head used for the apparatus. More, particularly, it relates to a magnetic head having a slider provided with a surface opposing a magnetic disk, which produces a lifting force for the magnetic head, and a magnetic recording and reproducing apparatus in combination of a magnetic head having a specified surface roughness and the magnetic disk.
It has been known heretofore that, in a magnetic recording and reproducing apparatus, there is employed a flying type magnetic head so designed that it flys with a microscopic gap from a magnetic recording medium by a minute air bearing which is formed due to the dynamic pressure caused when the magnetic recording medium is moved. Some conventional flying type magnetic heads are disclosed in, for example, Japanese Examined Patent Publication Nos. 21329/1983, 28650/1983 and so forth. The basic construction described therein is such that reading/writing elements are attached to the air discharge end of a slider having a flying plane on its one side opposed to a magnetic recording medium.
FIG. 11 is a perspective view of such exemplary conventional magnetic head, wherein there are shown a slider 1 composed of a ceramic material or the like, and reading/writing elements 2. The slider 1 has, on its one surface opposed to a magnetic recording medium, two rails 101, 102 which are spaced apart from each other and have flying planes 103, 104 defined with a high flatness. On the flying planes 103, 104, tapered portions 103a, 104a are formed at the inflow ends thereof relative to an air stream flowing in the direction indicated by an arrow mark a in combination with the magnetic recording medium. The reading/writing elements 2 are thin-layer elements produced by the same process as in the IC manufacture technology and attached to the air discharge end on the reverse side with respect to the tapered portions 103a, 104a.
In the use for a magnetic recording and reproducing apparatus, the magnetic head is secured to the fore end of an unshown gimbal support device and the flying planes 103, 104 of the slider 1 are brought into elastic contact with the surface of the magnetic disk. And the magnetic head held in such a state is driven in the so-called contact start-stop mode. When the magnetic disk is kept still, the flying planes 103, 104 of the slider 1 are pressed elastically against the dick surface. But upon start of rotation of the magnetic disk, as illustrated in FIG. 12, a lifting dynamic pressure is exerted on the flying planes 103, 104 of the slider 1 including the tapered portions 103a, 104a, so that the magnetic head is caused to fly by a flying height q based on the balance between such dynamic pressure and the resilient pressure P of the gimbal spring.
In this case, operations were carried out at a region where the flying height g was about 0.3 .mu.m.
In the conventional magnetic recording and reproducing apparatus of this kind, the flying height g of the magnetic head should be small as possible to realize high density recording. However, there has been a basic idea that the magnetic head has to be floated. In such circumstances, only measures have been taken to alter the shape of the rail portions or the tapered portions in order to reduce a flying height. Therefore, there was a limit in reducing the flying height.
The present invention is to break the limit of the conventional flying type magnetic recording and reproducing apparatus, and to provide a magnetic recording and reproducing system wherein a magnetic head is opposed to a magnetic recording medium with an extremely small flying height which can be considered to be a substantially contacting state (hereinbelow, referred to as a nearly contacting system). In order to realize a nearly contacting type magnetic recording an reproducing apparatus and a magnetic head used for the apparatus, it is necessary to resolve the following problem.
Since a magnetic head is actuated at an extremely small flying height which can be considered to be a substantially contacting state in such apparatus, a damage such as a crash of the magnetic disk may occur by the hiting of the magnetic head against the magnetic disk, and the durability is decreased.
On the other hand, when the surface properties of the magnetic disk are increased to thereby improve the durability, the magnetic head is apt be strongly attracted to the surface of the magnetic disk due to influence of moisture or water component in air. Since the conventional magnetic recording and reproducing apparatus of this kind is driven by a contact start-stop mode as described before, it becomes inoperable when the magnetic head is attracted to the disk.
As described above, when the nearly contacting magnetic recording and reproducing apparatus is manufactured, there arises a contradictory relation between the improvement of the durability and the prevention of a phenomenon of the attraction, which was difficult to resolve. Accordingly, the nearly contacting system has remained only as an idea.